The common wood pallet which has been the mainstay for storage and transport of goods of many kinds has become more of a burden on industry than heretofore. As transportation costs have risen, the concept of moving wood pallets back and forth for reuse, which has always been a burden on industry, has become economically prohibitive. Wood pallets offer excellent strength and durability, but even these desirable qualities have proven to be at best questionable justification for the continued use of these pallets.
Moreover, governmental regulations have been brought into effect which limit the ability to reuse or to dispose of any pallet, wood or otherwise, which has become contaminated with any of the hundreds of chemicals listed by the Environmental Protection Agency, for example. Damaged pallets can no longer be repaired economically if the portions thereof which are to be replaced are contaminated. Thus, there is an increasing need for pallets which are disposable economically under current and anticipated regulatory guidelines.
Regardless of their disposability, an acceptable pallet must possess the strength to support their intended loads, it must be sufficiently durable to withstand repeated use and including being lifted, while loaded, using the tines of a fork lift truck. Further, desirably the pallet must resist impregnation thereof by as many of the "contaminating" chemicals as possible, and must resist deterioration by the elements of the weather.
Still further, an acceptable pallet must be competitively priced in the marketplace.
It has been proposed heretofore that pallets be made up of corrugated paperboard, honeycomb paperboard, or other paperboard constructions. Two such pallets are disclosed in U.S. Pat. Nos. 4,977,446 and 5,218,913. These prior art pallets include base stringers and cross stringers each of which is made up from a unitary blank of corrugated cardboard. Multiple parallel panels of the blank are folded along score lines, for example, using an accordion fold or the like, into a core within which the several panels are disposed in side by side (stacked) relationship and thereafter are covered by others of the panels of the blank by folding these other panels about the core to define an outer covering for the core. These stringers are made up as individual components and then assembled into a pallet using mating notches formed in the base and/or cross stringers. This prior art pallet suffers from serious problems associated with its manufacture in that the folding requirements associated with the forming of the core and its integral outer cover impose impossible or impracticable dimensional requirements upon the blank. For example, the blank from which the stringer is formed includes a plurality of adjacent panels what are divided by fold lines. In order to form the desired notches in the folded product, several of the panels are initially die-cut with openings through the thickness of the blank at locations such that when the panels of the blank are folded, these openings overlie and are intended to be in register with one another to define the desired notches. Corrugated paperboard normally comes from the mill with a thickness dimension having a tolerance of +/-5 mils. Folding this corrugated paperboard into multiple layers tends to compound the effects of the thickness tolerance, so that the width and thickness dimensions of the resulting elongated stringers of this prior art pallet can not be held to that tolerance which is necessary for automatically assembling the stringers into a completed pallet. Especially, known manufacturing equipment is not capable of making up the stringers within the tolerances required for proper fit of the stringers when fitted within their mating notches or openings in other stringers. Also because of this inability to provide stringer components having acceptable dimensional tolerances, one is not able to assemble the base stringers and cross stringers into a stable pallet in which the base and cross stringers retain their desired right angle intersectional orientation at the crossover locations of the assembled stringers.
It has been suggested that the stringers be assembled with an interference fit between mating notches as a means to rigidify the pallet product, but again, the inability to maintain tolerances when folding unitary blanks of corrugated paperboard or the like, and attempting to develop notches in the product by registered individual pre-cut openings in the several panels, prevents the successful use of interference fits in the mating notches. As a consequence of the poorly-fitting of the notches of the stringers at their intersections, in use, when this and other similar prior art pallets are subject to the normal forces encountered in loading, moving and unloading goods on the pallet tend to "work" the mating notches at the intersections, with the result that these joints weaken quickly and the pallet no longer is usable. One other consequence of this inability to establish and maintain acceptable dimensional tolerances in this prior art pallet is the inability to obtain a level, smooth top (or bottom) plane containing the top surfaces of the stringers and onto which there can be applied a linerboard top sheet, for example.
It is an object of the present invention to provide a disposable pallet which is dimensionally stable.
It is another object of the present invention to provide a disposable pallet which can be manufactured, including assembly of the components thereof, expeditiously and economically.
It is another object of the present invention to provide a novel stringer or cross beam component for use in a disposable pallet.
It is another object of the present invention to provide a method for the manufacture of a stringer or beam component for use in the assembly of a disposable pallet.
It is another object of the present invention to provide a method for the manufacture of a disposable pallet.